#include<iostream>
#include<cmath>

using namespace std;

void grow(int &a) {// pass by reference
    a++;
}

void Swap(int &a, int &b) {
    int t = a;
    a = b;
    b = t;
}

int main() {
    int a = 3;
    grow(a);
    cout << a << endl;

    return 0;
}
